Beta-lactams Induced By Pseudomonas Aeruginosa Produce Free Of Endotoxin Research

-SW ox re IareerI0x OF PSooASAERUGINOSA--RELEASED LIPOP()LYSACCIIARIDE RESULTEDFs0' ect'--iscTw ANTIBIOTICSPostgraduate: Bu Yuehua(Phar'acology)Tutor: Cao YinglinAasTAncr0byective: to iuvestigate the antibacteria1 activity ofbata--lactam antibiotic ceftazicl ime (CTZ), imipcenm (lW) andmeyopenem (MEP) against pseudononas aeruginosa, incluc1ingantibioticinduced morphdogical changes and endotoxin--l iberatiugeffect. 'ethods: antibiotics,ere aolcle1 to four tinbes contani lus 5m1broth cultures to yieIcl a final concentrtion of 0. o Xmic, 1 X mic, 2X mic, 5X mic. A similar culture wi thout antibiotic acted as a growthcontrol and broth 'i thout bacteria or anti b iot ics 'as the med ium contro1.Samples(lm1) obtained at 0, 2, 4, 6, 12h after the addition of antibiotic'ere fiItered to exclude bound LPS (BLPS). FLPS content of seria1 di lutedfiltrates 'ere quantitat ive estimation at BET--32 bacteria endotoxindetector. 0bservation of bacterial morphology After centrifugation,broth cultures precipitate were smeared and stained with fuchsin toobserve the morphology change of thal1us in optical microscope. Results:3Effect of FLPS release when Pseudomonas aeruginosa were exposed to threekinds of antibiotics for different time the quantities of CTZ梚nducedFLPS was the most, the next was IMP, and MEP in last. Lower concentrationCTZ induced more FLPS and higher concentration induced fewer FLPS CTZmade bacterial morphology change from rod梥hape to filamentation, butminute quantities filaznentation with lysis status were remained. IMPand MEP made thallus keep original rod or spher梤od shape. Conclusion:There is no significant difference in bactericidal capability and antibacterial activity among three ~ 條actam antibiotics, CTZ, IMP and MEP against Pseudomonas aeruginosa. CTZ, IMP and MEP can induce Pseudomonas aeruginosa to release large amounts of FLPS. CTZ>IMP> MEP, in inducing intensional sequence. Lower concentration CTZ induced more FLPS and higher concentration CTZ induced fewer FLPS. This experiment suggest that when clinically selecting antibiotics against GNB infection, we should not only select those drugs with faint side effect and strong antibiotic activity but also consider the effect of endotoxemia on treatment. Consequently, it?s better to choose those antibiotics which induce GNB to release fewer FLPS, even no FLPS.